According to the black body radiation law, any object above absolute zero in nature keeps radiating energy to the exterior. The radiated energy and the wavelength distribution highly depend on the surface temperature of the object: The higher the surface temperature of the object, the higher the infrared radiated energy. The infrared thermometer accurately measures a human body skin surface temperature by obtaining the infrared radiated energy of human body skin surface through an infrared receiving sensor and, with help of an algorithm in it, corrects the temperature difference between the forehead temperature and the actual human body temperature with help of the algorithm in the thermometer, thus obtaining the accurate human body temperature. At present, there are three main infrared thermometers on the market, i.e. universal infrared ear thermometers, infrared non-contact thermometers and infrared contact thermometers. Universal infrared ear thermometers: Hypothalamus is an important temperature control organ in the brain and close to ears. Any change of the mean temperature deep in the human body results in a quick change of the temperature in the ears. Interiors of the ears are closed areas not much influenced by the exterior. Thus, the ear temperature is closest to the actual human body temperature. Infrared ear thermometers realize human body temperature measurement by measuring the infrared radiated energy of ear canals and tympanic membranes and are advantageous in accurate temperature measurement. Infrared non-contact thermometers: The forehead is close to the heart and has quick circulation of blood supplied by the large artery and the carotid artery via the temporal artery, so it can suggest human body temperature changes truthfully and in time. When a person has a fever, his brain will be affected first. Upon a temperature change, the brain will begin to adjust the human body first. As a result, the forehead surface temperature will show temperature change quickly. Infrared non-contact thermometers realize human body temperature measurement by measuring the infrared radiated energy of people's foreheads. Each infrared non-contact thermometer can realize accurate measurement even when it is some distance from one's forehead because it has a special non-contact temperature measurement channel for controlling the measured area and strengthening the infrared signal. Infrared contact thermometers: They realize human body temperature measurement by measuring the infrared radiated energy of people's foreheads as non-contact thermometers do; however, they need to be close to people's foreheads for accurate measurement because it needs short measuring distances as a result of inexistence of a special non-contact temperature measurement channel. The existing infrared non-contact thermometers on the market cannot realize ear temperature measurement but be used separately only, making it necessary for a user to buy both an ear thermometer and a non-contact forehead thermometer for the purposes of ear temperature measurement and non-contact forehead temperature measurement. The existing ear thermometers and integrated contact thermometers are disadvantageous in inaccurate temperature measurement and cross infection risk because of short measuring distances or contact with skin and temperature rising in measurement.